It is known, as for example from my U.S. Pat. No. 3,403,633, to provide the underside of an amusement-ride car of the rail type with a drive member that constitutes a bar extending longitudinally in the transport direction. This bar is engaged transversely on both sides by oppositely effective drive rollers that are driven to impart motion to the car and other cars attached to it. Such an arrangement is used in rail-type rides of the roller-coaster type.
The drive member must be able to transmit considerable longitudinal forces from the drive wheels that engage it to the car it is carried by. Accordingly this drive member is normally made very rigid and, in fact, is frequently constituted as a downwardly projecting sort of ventral rib on the car. As the car moves above the drive rollers these rollers grip the drive member and push it and the car along.
It is necessary that the drive member remain centered between the drive rollers. Accordingly in an arrangement having a curved track it is standard practice to form the drive member of the same radius of curvature as the track, so that it remains centered between the drive rollers. Similarly when used in a straight section of track the drive member is normally perfectly straight.
The disadvantage of these systems is that minor maladjustments of the drive rollers or of the drive member frequently result in only one of the drive rollers engaging the drive member so that insufficient force can be transmitted to the car. Similarly it is frequently necessary to provide several driving stations along a single track. When this is done it is essential that they all be placed in a track portion of the same curvature, or all in straight sections. It is impossible with the prior-art drive member to provide some drive-roller sets in curves and others in straight sections due to the drive-member configuration.